1. Field of the Invention
The present invention relates to computer controlled machines, and more specifically, it relates to a small, non-contact optical sensor that increases the capability and flexibility of computer controlled machines by detecting its relative position to a workpiece in all six degrees of freedom.
2. Description of Related Art
In today's flexible manufacturing operations, much time and money are wasted when changes have to be made in the manufacturing process. For example, if a minor modification is made to the shape of a car door and a robot is used to weld that door, the robot must be "taught" the new shape by an operator. That is, the operator must guide the robot tool by hand through each motion and every orientation in the welding operation. Besides being time consuming, this process is often inaccurate. It is also expensive because this is down time for both the robot and the operator. Furthermore, every part must be positioned exactly where the robot expects it to be, requiring the use of expensive sensors and positioning devices.
Many companies make non-contact laser sensors. Most are one dimensional (1D) range detectors, a few construct a 3D profile of an object, but the object must move through its laser beam. By scanning a laser beam, a laser range camera can detect all 3 positions of a stationary object, and even though it does not detect orientation, it appears to be SixDOF's closest competitor. Laser coordinate measuring systems (laser trackers) also detect three positions of a stationary object, but, made for large work volumes, they are too big (&gt;1 ft.sup.3) and too expensive (.about.$140,000) to mount on a robot or machine head.